digestive system

• what are the two roles of the digestive system?

  digestion and absorbtion
• digestion is the process of breaking down large food molecules into small food molecules.
• absorption is the process of absorbing small molecules into the body
• the stomach produces pepsin which is a protease enzyme and breaks proteins down into amino acids.
• the stomach produces hydrochloric acid which maintains the right ph for pensin
• the stomach contracts its muscular walls to mix food.
• bile is made in the liver but is stored in the gall bladder.
• after a meal bile is released into the small intestine.
• bile emulsifies lipids separating large fat droplets into smaller ones.
• bile also neutralises acids in stomach since its alkaline.
• the pancreas produces amylase protease and lipase
• the small intestine produces amylase protease and lipase
• villi are in the intestine and are responsible for absorbing nutrients into the body.
• there are many villi which gives them a large surface area to absorb nutrients.
• they have a single layer of cells so nutrients only have to travel a short distance making the process quick
• villi have a strong blood supply which maintains a strong concentration gradient.
• main role of the large intestine is the absorb water.
• the mouth chews food and breaks it down
• salivary glands produce saliva which contain amylase to breake down starch into maltose
• the pancrease produces pancreatic juices and sends it to the small intestine